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SIMPLEX
Problems, Solutions and Construction notes
This page highlights the main problems encountered by those building Simplex. Also included are contruction notes relating to suggested modifications to the design.
3. Missing details from the drawings.
4. Missing information from the drawings.
| Q. | The basic Simplex design does not incorporate any brakes, however Martin Evans suggest that they can be added if required. Where can suitable details be found? |
| A. | The hand brake
arrangement detailed for Super Simplex can be
incorporated into the standard Simplex with very little
modification. Super Simplex has an axle pitch of 7.3/8
& 7.5/8 compared to 7.1/8 all round for Simplex, this
means that the operating rods are shorter than
illustrated. To aid adjustment all brake operating rods
can be fitted with hexagon turnbuckles tapped 5BA at one
end and 5BA left hand at the other. As the wheel size and the lower frame edge to running height is the same for both locomotives, the position of the brake hanger pins will be the same at 1.3/4 up from the bottom of the frame and 2.1/2 ahead of each axle centre. The brake standard is fixed outside the right hand frame 3.7/8 ins forward from the outside face of rear buffer beam. The mounting bracket, of 1" x 1" brass angle, is flush with the top edge of the frame. On Super Simplex the brake cross shaft is mounted in bushes near the bottom edge of the frames. As the Simplex frame profile is different it is necessary to mount this shaft in brackets fitted to the lower edge of the frames. These brackets are bolted to the frames just behind the rear vertical stretcher and provide the pivot at 3/8 below the lower frame edge at this point. All crank levers fitted to this cross shaft are taper pinned in position. A problem arises with front hangers which foul the cylinder rear covers therefore it necessary to mill a flat on each cover inner face for clearance. (For dates of articles for Super Simplex see Frequently Asked Questions ). |
| The following is an issue raised by Colin Abrey relating to the rating of the springs specified for Simplex. This is included for information and should not be assumed to be correcting an error in the original design, rather one constructors approach to this particular item. |
| From the data published in
various IMLEC reports it would seem that the all up
weight of Simplex is around 120lbs which, if the weight
is evenly distributed, gives a load of 40lbs per axle
(ignoring the weight of wheels & axles which are
unsprung). As there are four springs per axle then the
load will be 10lbs per spring. The springs I have fitted are GLR No 13 which are (nominal) 3/8 OD, 7/32 ID and have 7 free coils of 17 SWG wire. (There are no springs specified on the drawings, however the ME articles and book specify Using a spring nomogram the stiffness works out at 70 to 80lbs/inch, so 10lbs will give a deflection of approximately 1/8 inch. I believe that with zero (or very little) pre load on each spring, the completed locomotive should settle at the correct running height which is with the axle boxes 1/8 inch clear of the horn keeps. However I note that, in the Super Simplex article, Martin Evans has included details of the axle box springs which are smaller in diameter and use a thinner wire gauge. |
3. Missing details from the drawings.
The following is a list of information not included either on the drawings or in the book. However they are all covered in the articles published in the Model Engineer.
Item |
Reference in articles in model engineer |
Blower valve |
7th June 1968 Page 546 |
Snifting valve |
7th June 1968 Page 546 |
Blower union |
7th June 1968 Page 546 |
Regulator detail |
5th July 1968 Page 650 |
Regulator handle |
5th July 1968 Page 650 |
Water gauge |
5th July 1968 Page 650 |
Manifold |
5th July 1968 Page 651 |
Check valve |
5th July 1968 Page 651 |
Blowdown valve |
20th September 1968 page 917 |
4. Missing information from the drawings.
Where appropriate, comments anoted (ME) are the response provided by Martin Evans to the specific query.
| Item | Description | Comments |
| SHEET
1 Guard Irons |
These are shown on the GA, but no details are provided. Position and fixing holes on the mainframe are not shown. | These should be measured off the drawings (ME). |
| SHEET
1 Cast horns |
The size, position and number of rivets is not shown on the drawings. | |
| Sheet
2 Cylinders and axle pump |
Packing
material for glands. Dimensions for positioning steam chest fixing screws. |
|
| Sheet
2 Hornstays |
Should longer hornstays be specified for cast horns which are wider than the fabricated versions. | The drawing on page 447, April 17th 1987 shows that the width of the horn stays matches the cast horns. (ME). |
| Sheet
4 Exhaust tee. |
What is the material for the exhaust tee, and what are the hexagon sizes for the lock nuts. | This may be brass or gunmetal. The locknuts are made from brass or gunmetal, and should be a reasonable width across flats, according to their thread, e.g. 1/2 inch A/F would be about right for 5/16 x 32t. 9/16 inch A/F would be about right for 3/8 x 32t.(ME) |
| Sheet
6 Bunker tank |
Is it fixed to the frames? | No, the bunker tank rests on top of the running board, and can be secured by a short piece of brass angle, say 3/8 x 3/8 at the front end and a similar piece at the rear clearing the stub pipe which carries the water to the bunker tank. (ME) |
| Sheet
6 Spectacle plate |
How is it attached to the cab sides. Is it positioned flush with the cab front? | The spectacle plate is fitted to the cab sides by brass angles. The angle need not be carried further downwards below the level of the top of the side tank. It is flush with the sides.(ME) |
| Sheet
6 Bunker |
How is it attached to the cab sides? | Most builders make the bunker water tank so that it is a close fit within the bunker sides/cab sides/bunker back, so that there is no need to bolt it in.(ME) |
| Sheet
6 Cab floor |
The text indicates that the cab floor is above the tank interconnecting water pipes, but the drawings do not provide sufficient information on how it is supported. One angle is shown on the bunker assembly, but its position is not defined. | Most builders prefer to deal with the matter of the cab floor in their own way. Clearly when you have reached this point in construction, you will be able to see very clearly what to do about this. (ME) |
| Sheet
6A Axle pump |
Transfer position relative to bore. | As the top surface of the feed pump is generally left as cast, it might be unhelpful to put a dimension here. A good look at the position of the transfer passage in relation to the position of the ball on the right hand end of the pump should enable one to decide where to drill it. (ME). |
| Springs
generally Safety valve Oil check valve Buffer springs Axle box spring (see above) |
Wire thickness, free length, number of turns. | The great majority of beginners will purchase their springs from advertisers in the Model Engineer, ( see Frequently Asked Questions for contacts) and these suppliers list the correct springs for every application on a model like Simplex. (ME). |
Martin Evans describes Simplex as being lubricated via a traditional mechanical lubricator, located on the running board, and driven from the valve gear. An alternative is to use displacement lubrication, which was described by Keith Gammage in the Model Engineer volume 182 No. 4091 dated 9-22 April 1999.
The text is available either as a 'text' file, or as a zipped Word file. The drawings are in two files, the first is AutoCAD files (.dwf), the second bitmap (.bmp) files.
All of these have been zipped to compress them. If you do not have anything which will 'un-zip' them, you can download a free evaluation copy of Winzip from www.winzip.com .
The attached zipped Word file describes a problem encountered by Colin Abrey
when trying to mount the water pump.
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